An interesting study at Vanderbilt University (something not quite right about the brain picture on that page) suggests that consciousness is not narrowly localised within small regions of the cortex, but occurs when lots of connections to all regions are active. This is potentially of considerable significance, but some caution is appropriate.

The experiment asked subjects to report whether they could see a disc that flashed up only briefly, and how certain they were about it. Then it compared scans from occasions when awareness of the disc was clearly present or absent. The initial results provided the same kind of pattern we’ve become used to, in which small regions became active when awareness was present. Hypothetically these might be regions particularly devoted to disc detection; other studies in the past have found patterns and regions that appeared to be specific for individual objects, or even the faces of particular people.

Then, however, the team went on to assess connectedness, and found that awareness was associated with many connections to all parts of the cortex. This might be taken to mean that while particular small bits of brain may have to do with particular things in the world, awareness itself is something the whole cortex does. This would be a very interesting result, congenial to some, and it would certainly affect the way we think about consciousness and its relation to the brain.

However, we shouldn’t get too carried away too quickly. To begin with, the study was about awareness of a flashing disc; a legitimate example of a conscious state, but not a particularly complex one and not necessarily typical of distinctively human types of higher-level conscious activity. Second, I’m not remotely competent to make any technical judgement about the methods used to assess what connections were in place, but I’d guess there’s a chance other teams in the field might have some criticisms.

Third, there seems to be scope for other interpretations of the results. At best we know that moments of disc awareness were correlated with moments of high connectedness. That might mean the connectedness caused or constituted the awareness, but it might also mean that it was just something that happens at the same time. Perhaps those narrow regions are still doing the real work: after all, when there’s a key political debate the rest of the country connects up with it; but the debate still happens in a single chamber and would happen just the same if the wider connectivity failed. It might be that awareness gives a wide selection of other regions a chance to chip in, or to be activated in turn, but that that is not an essential feature of the experience of the disc.

For some people, the idea of consciousness bring radically decentralised will be unpalatable. To them, it’s a functional matter which more or less has to happen in a defined area. OK, that area could be stretched out, but the idea that merely linking up disparate parts of the cortex could in itself bring about a conscious state will seem too unlikely to be taken seriously. For others, who think the brain itself is too narrow an area to fully contain consciousness, the results will hardly seem to go far enough.

For myself, I feel some sympathy with the view expressed by Margaret Boden in this interview, where she speaks disparagingly of current neuroscience being mere ‘natural history’ – we just don’t have enough of a theory yet to know what we’re looking at. We’re still in the stage where we’re merely collecting facts, findings that will one day fit neatly into a proper theoretical framework, but at the moment don’t really prove or disprove any general hypotheses. To put it another way, we’re still collecting pieces of the jigsaw puzzle but we don’t have any idea what the picture is. When we spot that, then perhaps the pieces will all… connect.

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Posted by Peter on April 4, 2015 at 1:12 pm.
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2 Comments

1. Hunt says:

I think Boden is right about imaging, and the problem, I think, is their deficiency in creating constraints. Describing nature (“natural history”) isn’t how you aggressively discover things in science, though I’m not saying it’s pointless. It’s how masses of information are collected.

Aggressive scientific discovery sets up constraints that progressively quarry its target. It continues to ask the question “what must be true, given what we know” as it spirals inward to a solution, and once it has excluded possibilities, it usually doesn’t waste time reconsidering them. This may seem a bit rigid, but it’s the only system that effectively controls problem complexity. The rare times when it fails, it’s usually time for a Kuhnian revolution.

I actually think consciousness studies would be further along if researchers learned to think more “inside the box” rather than out of it.

2. Sci says:

I think there is a place for philosophy, but philosophers also seem to be happy to latch on to aspects of science that fits in with their personal viewpoint. Hard to trust someone without a STEM degree making assumptions about science IMO, since a lot of science fanboys are confined to reading pop-sci and have only as much a grasp as the rest of us. (OTOH, scientists also do bad philosophy.)

Along the lines of what Hunt said seems to me one way to cut through the chaff is to demand theories should predict aspects of neurobiology and provide some advancement in medicine and/or technology.

Might be the best way to solve the “What brain wiring brings about consciousness?” question, at which point we can move on to the actual Hard Problem. Ideally more (but not all) funding should go to the theories that have had success with the above requirements, and we test those to exhaustion.